1. LVL AS A CONSTRUCTION MATERIAL 1.12.8 Surface coating of LVL LVL can be painted with fully pigmented non-transparent paints or stained with translucent stain or varnish. Due to peeling cracks, the surface of LVL is more demanding to paint than, e.g., solid wood. The cracks occur in the face veneers as a result of contraction and swelling of the product. In indoor conditions these cracks are not usually problematic, but in applications exposed to weather, a pigmented covering paint is required to protect the LVL. If the moisture nevertheless penetrates the LVL member, for example at the penetration points of connectors, at the edges or other similar areas, a thick paint coating will tend to flake. This is especially evident on large continuous surfaces. If surface cracks are not problematic for the application in question, a light non-film-forming surface treatment can be a suitable alternative. This may require more frequent maintenance, but the maintenance treatment is easier to perform. The durability of the coating depends on various factors: the base material and how it has been prepared; the level of Figure 1.66. Coated surfaces of LVL beams. exposure to sunlight; the colour and darkness of the coating; and the level of exposure to moisture. General guidelines for coating LVL: • Apply the coating as soon as possible to prevent the effects of UV radiation on the wood surface. If needed, sand the surface prior to coating. • Fill any voids, such as fallen knots, with substitute wood compound. • Choose a primer with blue stain and mould protection. • Round the edges of the member slightly to ensure adherence of an adequate thickness of coating also on the edges. Edge coating is especially important for all veneer-based wood products. • Apply the coating agent to an adequate thickness. Apply the coating agent in at least two layers to ensure proper drying of the layers. In all cases of coating LVL the application should be discussed in detail with the coating agent manufacturer to ensure the suitability of the product for the application 21. Stora Enso 48 LVL Handbook Europe
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